Field of the Invention
The present invention relates generally to an organic light emitting diode (OLED) display. More specifically, the invention relates to an OLED display which provides an improvement in aperture ratio while increasing storage capacitance.
Description of the Related Art
An organic light emitting diode (OLED) display includes two electrodes and an organic emission layer disposed between the two electrodes, and electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer so that excitons are formed, and light is emitted by energy generated from the excitons.
In each pixel of the OLED display, a plurality of switching thin film transistors are formed to compensate for non-uniformity of a threshold voltage of driving thin film transistors and deterioration of an organic light emitting diode. In this case, an initialization voltage that initializes the driving thin film transistor is applied to the driving thin film transistor through an initialization voltage line.
Furthermore, in order to improve visibility of the OLED display, a green pixel having excellent visibility is further provided, and thus an OLED display of four color pixels has been applied, and the four color pixels can be arranged according to various types such as a stripe type, a checker type, or pentile type.
In particular, in the four color pixel OLED display, initialization voltage lines are respectively formed in two pixels in one row and in two pixels in an adjacent row, and in this case, each pixel should include an initialization contact hole for connection of the driving thin film transistor of each pixel with the initialization voltage line.
However, pixels of a high resolution OLED display tend to be down-sized, and accordingly a space for a storage capacitor is reduced due to an initialization contact hole formed in each pixel, and an aperture ratio is also decreased due to the initialization contact hole formed in each pixel.
The above information disclosed in this Background section is only for enhancement of an understanding of the background of the described technology, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.